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https://issues.apache.org/jira/browse/CALCITE-1003?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15046366#comment-15046366
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Julian Hyde commented on CALCITE-1003:
--------------------------------------
[~amargoor], Thanks for the PR. I have done some work on it, eliminating
duplicate code between JdbcRules and RelToSqlConverter by creating a new class
SqlImplementor. I changed Context.ignoreCast to false, and found a
different/better way to ignore trivial casts. I also incorporated fixes for
CALCITE-970 and CALCITE-893 that had been missed in your copy of the code.
See my https://github.com/julianhyde/calcite/commits/1003-rel-to-sql branch, in
particular commit 69e20934. Can you please review, and check that your tests
still run successfully on RelToSqlConverter. It would also be good to have some
tests that use the OFFSET and FETCH clauses.
> Add Utility to convert RelNode to SqlNode
> -----------------------------------------
>
> Key: CALCITE-1003
> URL: https://issues.apache.org/jira/browse/CALCITE-1003
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Amogh Margoor
> Assignee: Julian Hyde
> Priority: Minor
> Fix For: next
>
>
> To track progress on Rel2Sql Converter.
> Following is the email conversation that lead to this JIRA:
> {quote}
> On Wed, Dec 2, 2015 at 3:13 AM, Julian Hyde <[email protected]> wrote:
> Yes, this would definitely be useful in Calcite. Thanks for offering.
> I would like to reduce the amount of code copy-pasted from the JdbcXxx
> relational expressions, but we can work on that after it is committed in and
> when there are some unit tests.
> Can you please create a JIRA case with an initial pull-request?
> I think the unit tests could be of the following form:
> {code}
> @Test public void testScan() {
> final String sql = “select * from emp”;
> final String after = "SELECT *\n”
> + "FROM \”EMP\””;
> check(sql, after);
> }
> {code}
> where “after” is the result of the round trip SQL => SqlNode => RelNode
> => SqlNode => SQL, and your utility is performing the 3rd “=>”.
> Julian
> > On Dec 1, 2015, at 12:28 AM, Amogh Margoor <[email protected]> wrote:
> >
> > Hi,
> > We have an usecase where we need to just send back optimized query as
> SQL,
> > without executing it. So we needed an utility to convert RelNode back to
> > SQL, and found most of the logic to be in JDBCRel. As we needed it for
> non
> > JDBC source, we created an utility to do so:
> >
> https://github.com/amoghmargoor/incubator-calcite/blob/NEZ-52/core/src/main/java/org/apache/calcite/rel/rel2sql/RelToSqlConverter.java
> >
> > Utility is almost completely copy-pasted from JDBCRels with few fixes
> from
> > our side to make it work. If such utility will be useful in Calcite then
> > let us know, we can plan raising PRs with required UTs.
> >
> > Regards,
> > Amogh
> {quote}
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